Li-Ion Batteries Using Low-Cost Alloy Anodes

The PIs have recently invented a series of electrolytes that enable anodes based on micron-sized silicon (µSi) with high-voltage cathodes such as NMC and NCA. These have been used to form full cells and achieved high coulombic efficiency (CE) of > 99.9% and long cycle life of > 300. The novel electrolytes have demonstrated the following characteristics: (1) enabling 5-10µm Si anode to achieve a capacity exceeding 2800 mAh/g at an areal capacity of 6 mAh/cm2; (2) having an electrochemical stability window exceeding 4.5 V, enabling the use of NMC/NCA cathodes to achieve CE of > 99.9%; (3) having ionic conductivity of > 5 mS/cm; (4) a projected calendar life up to 10 years (based on extrapolation). The silicon anode is composed of > 60% µSi, along with graphite, carbon black, and binder. Additionally, µSi has a cost of approximately $5/kg, which is lower than the cost of batterygrade synthetic graphite (approximately $15/kg). If commercialized, µSi technology is expected to provide anodes at a lower cost and with higher capacity than synthetic graphite anodes. The combination our novel electrolyte and µSi can overcome the inherent flaws of nano-silicon anodes, including: (1) high cost, (2) irreversible swelling, (3) continuous gas generation, electrolyte consumption, and pressure buildup during usage, and (4) short calendar life. In this work, we propose to design novel electrolytes that enable the production of µSi/NMC pouch cells with a capacity exceeding 2 Ah to achieve a specific energy of over 400 Wh/kg at the cell level. The electrolyte is non-flammable, providing an major safety advantage over current commercial Li-ion batteries. In phase I, WH-Power, Inc. and University of Maryland team will (1) optimize alloyed anode slurry and coating with over 60 wt% µSi loading, (2) assemble and test pouch cells with a capacity exceeding 2 Ah using commercial NMC532 cathodes for their cycle life, calendar life and operation temperature range, (3) use waste solar cell as silicon raw material to produce batteries. The development of the anode coating, pouch cell battery assembly, and pouch cell testing will be conducted by WH-Power. The electrolyte development will be subcontracted to Dr. Chunsheng Wang at the University of Maryland.